Deputy Attorney General Rod Rosenstein has appointed a special counsel to oversee the investigation into Russian influence in the 2016 election, ending weeks of speculation about how Rosenstein would respond to the growing chorus of lawmakers and advocacy groups calling for such a move.

Rosenstein has named former FBI director Robert Mueller, the Justice Department has confirmed.

“In my capacity as acting Attorney General, I determined that it is in the public interest for me to exercise my authority and appoint a Special Counsel to assume responsibility for this matter,” Rosenstein said in a statement. “My decision is not a finding that crimes have been committed or that any prosecution is warranted. I have made no such determination. What I have determined is that based upon the unique circumstances, the public interest requires me to place this investigation under the authority of a person who exercises a degree of independence from the normal chain of command.”

The decision about whether to appoint a special prosecutor was Rosenstein’s to make, not Attorney General Jeff Sessions'. Sessions is recused from any investigations into matters related to the 2016 election, per a recusal policy that he announced in March.

President Trump’s decision to fire James Comey as FBI director on May 9 reignited pressure on Rosenstein to appoint a special counsel. Trump’s critics charged that the firing was rooted in Comey’s pursuit of the Russia probe — a claim the administration has denied — and a series of damaging news reports this week about Trump’s interactions with Russian officials and his exchanges with Comey focused the spotlight on Rosenstein. Rosenstein wrote the initial memo the administration used as justification to fire Comey, over his handling of the Clinton email investigation.

Trump issued a statement on Wednesday evening that didn't directly mention Mueller or the special counsel appointment, saying only that he "looked forward to this matter concluding quickly."

"As I have stated many times, a thorough investigation will confirm what we already know — there was no collusion between my campaign and any foreign entity," Trump said.

Rosenstein wouldn’t commit to appointing a special counsel for the Russia probe at his confirmation hearing in early March, saying that he couldn’t make such a pledge without all the facts. He defended the department’s ability to conduct an independent investigation, but said that he would “ensure that every investigation is conducted independently.”

Rosenstein said in his statement Wednesday that although he has “great confidence” in the independence and integrity of the department, he concluded that a special counsel is needed “in order for the American people to have full confidence in the outcome.”

Senate Majority Leader Mitch McConnell said in a statement that the Senate Select Committee on Intelligence would continue its investigation into Russian intervention in the election. In a joint statement, Sens. Richard Burr and Mark Warner — the chair and vice chair of the intelligence committee, respectively — said that "to the extent any deconfliction is required, we will engage with Director Mueller and our expectation is that he will engage with the Committee as well."

"The decision by the Deputy Attorney General to appoint former FBI Director Robert Mueller as a special counsel confirms that the investigation into Russian intervention into our election will continue, as stated last week by Acting FBI Director Andrew McCabe," McConnell said.

Mueller was James Comey’s predecessor as FBI director, serving from 2001 to 2013. After leaving the FBI, he went to a private law firm in Washington, DC, Wilmer Cutler Pickering Hale and Dorr. His law firm bio page was no longer active as of Wednesday evening. The Justice Department said Mueller had resigned from the firm to avoid any conflicts of interest with members of the firm or its clients.

"I accept this responsibility and will discharge it to the best of my ability," Mueller said in a statement provided by Wilmer.

Two other Wilmer lawyers have left the firm and are expected to join Mueller, according to a firm spokesman: Aaron Zebley and James Quarles. Zebley was Mueller's chief of staff at the FBI, and followed him to Wilmer. Quarles is a longtime Wilmer attorney and served as an assistant special prosecutor on the Watergate Special Prosecution Force in the mid-1970s.

Mueller is no stranger to the position of special counsel. During his tenure as FBI director, the Justice Department in 2003 brought in a special counsel to investigate the leak of the identity of undercover CIA officer Valerie Plame. At the time, Attorney General John Ashcroft was recused from the investigation, so the decision fell to his deputy attorney general, James Comey — the now-former FBI director whose role in the Russia probe has fueled speculation that it may have led to his firing by President Trump.

Under federal regulations, a special counsel appointed under these circumstances isn’t subject to “day to day” supervision by any official at the Justice Department. However, Mueller will answer to Rosenstein, who is the lone official with the power to remove him “for misconduct, dereliction of duty, incapacity, conflict of interest, or for other good cause.” If Rosenstein decides not to follow an action proposed by Mueller because he thinks it’s inappropriate or unnecessary, Rosenstein is required to tell Congress.

Senate Judiciary Committee Chair Chuck Grassley said in a statement that Mueller "comes with the right credentials for this job."

"The FBI’s handling of recent politically charged investigations has eroded the public’s trust in its ability to be independent. I have a great deal of confidence in Deputy Attorney General Rosenstein and I respect his decision," Grassley said.

California Sen. Dianne Feinstein, the ranking member of the Senate Judiciary Committee, said in a statement that Mueller’s appointment was “a good first step.”

“Bob was a fine U.S. attorney, a great FBI director and there’s no better person who could be asked to perform this function. He is respected, he is talented and he has the knowledge and ability to do the right thing,” Feinstein said.

Several Democratic senators tweeted shortly after news broke Wednesday night that they were pleased with Rosenstein’s decision, adding that they will work to ensure that Mueller has the resources he needs to continue the investigation. “This is a victory for all Americans who believe in the integrity of the rule of law,” Oregon Sen. Jeff Merkley tweeted.

"Robert Mueller has the experience and expertise, guts and backbone necessary to uncover the truth and hold wrongdoers accountable," Sen. Richard Blumenthal, a Democrat on the Judiciary Committee, said in a tweet.

Congressional Republicans had largely positive reactions to the news of Mueller's appointment. New York Rep. Peter King said he did not believe a special counsel should have been appointed. "It's always a dangerous precedent to set," he said. But, he went on, "if you have to have one, Mueller's a very good choice."

"I support the decision," said North Carolina Rep. Mark Meadows. "I don't know enough about Mueller to suggest whether he's fair or not. The only thing I know about him is when there was IRS targeting he didn't seem to know about it, so that would say from my standpoint I think he'll be fair and impartial."

Rosenstein is scheduled to brief the Senate on Thursday in a closed-door meeting, following up on Comey’s testimony before the Senate Judiciary Committee shortly before he was fired on May 9.

Rosenstein spoke to a Baltimore business group on Monday — prior to his confirmation this year as deputy attorney general, he was the longtime US attorney in Maryland — and said that "courage in government" meant "standing on principle, ignoring the tyranny of the news cycle, resisting the urge to spin, remaining focused on the things that matter," according to the Baltimore Sun.

"I took an oath to preserve, protect, and defend the Constitution of the United States. There is nothing in that oath about my reputation," Rosenstein said. "If you ask me, one of the main problems in Washington, DC, is everybody is so busy running around trying to protect their reputation instead of protecting the republic, which is what they're supposed to be doing."

“Lol. I can't wait till they find nothing. Liberal meltdown will go into full steam. People listening to the same media that got your hopes up about Hillary and then....suprise! You still put full faith in them. Definition of sheep.”

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Zoe Tillman is a legal reporter with BuzzFeed News and is based in Washington, DC.